Hydraulic suspension system for vehicle with level corrector and balancing of front and rear axle reactions



March 25, 1958 A. BREDER 2,828,138

.HYDRAULIC SUSPENSION SYSTEM FOR VEHICLE WITH 1 LEVEL CORRECTOR AND BALANCING OF FRONT AND REAR AXLE REACTIONS 2 Sheets-Sheet '1 Filed May 3l, 1955 Z-/VVETO R A/vromE BRUEDER ATTORNEY March 25; 1958 I A. BRUEDER HYDRAULIC sUsPENsIoN SYSTEM EOE VEHICLE WITH LEVEL CORRECTOR AND EALANCING OF- FRONT AND REAR AXLE REACTIONS 2 Sheets-Sheet 2 `Filed May 51, 1955 Fgf 2 Anfon/5 B/Puf 5,1? 5) T0 Vf United States Patent 'O HYDRAULIC SUSPENSION SYSTEM FOR VEHICLE WITH LEVEL CORRECTOR AND BALANCING OF FRONT AND REAR AXLE REACTIONS Antoine Brueder, Paris, France, assignor to Socit Anonyme Andre Citroen, Paris, France Application May 31, 1955, Serial No. 512,073

Claims priority, application France February 23, 1955 4 Claims. (Cl. 280124) The essential object of this invention is to provide in a hydraulic suspension system for vehicle a device adapted to maintain the vehicle frame at a constant level above the road surface irrespective of thefload supported by the suspension system, and wherein the reactions of the front and rear axle are always equal to each other.

This invention is also concerned with a suspension system wherein one of the trains of wheels is provided with a device effecting both the level correction and the balancing of the suspension system.

It is another object of this invention to provide a device wherein the equality'between the reactions of the front and rear axles is attended at ythe same time by the unvarying height of the vehicle frame above the ground, this specific feature being obtained by using a device of the type described and illustrated in the U. S. patent apn plication Ser. No. 422,635 led by the same applicant on April 12, 1954, now Patent No. 2,757,376, dated July 3l, 1956.

These various objects are obtained according to this invention by providing on the one hand for each train ofwheels a level correction operatively connected to a hydro-pneumatic suspension system, and on the other hand an action exerted on the assembly of one train of wheels according to the average' height represented by the position of the middle of the suspension member of the train concerned, the resilient condition of the suspension and the aforesaid level-correcting action depending from each other.

The attached drawings forming part of this specilication illustrate diagrammatically by way of example one form of embodiment of an inter-action suspension system having the constant-height characteristic, the arrangement comprising axle-supporting swinging arms and torsion bars.

In the drawings:

Figure 1 is a diagrammatic view showing the principle of the invention.

Figure 2 is a detail view showing the correction-controlling distributor according to Fig. l; and

Figure 3 is a detail View showing the hydraulic suspension chamber.

1.--Frnt axle (Fig. 1)

Each swinging arm 1 carrying the stub axle 2 of a wheel 3 has connected thereto the rod 4 of a piston 5 slidably mounted in a cylinder 7 secured on the frame of the vehicle. An anti-roll torsion bar 8 is mounted between the pair of front swinging arms to limit the transverse movements thereof; the pair of front suspension cylinders 7 positioned on the left and right sides of the suspension system are interconnected through a pipe line 11 and a common pipe line 12 leads from this pipe 11 to the suspension chamber 13.

An anti-hunting spring 14 is located between the piston and the bottom of the cylinder 7 of each wheel suspension. The spring load represents a fraction of the Hee reaction produced on the piston, this fraction being as small as possible.

A height corrector 16 already known per se is controlled by the angular displacement of the anti-roll torsion bar 8 by means of an arm 15 and a suitable transmission rod. This corrector is adapted to add fluid to or remove it from the chamber 13 and is connected to this chamber through a pipe line 51 so as to keep the vehicle to a constant height, irrespective of the load.

The hydraulic assembly is fed `with fluid under pressure from the accumulator 29, through the pipe line and corrector 16, but the portion acting upon the rear wheel assembly must be separate from the portion acting upon the front wheel assembly, so that the latter alone will receive the volume of corrector iluid; therefore, the minor leaks likely to gradually drain off the fluid from the portion acting upon the rear wheel assembly must be compensated. This is the function devolved to the com munication illustrated between the two ends of the cylinder 13, and the jet G is interposed in the pipe line 38 to p prevent any undue amount of luid from being transferred during the reactions of the suspension system. l

II.-Rear axle i pivoted at 17 on the central portion of a link 20 pivoted in turn at one end 50 on the rod 49 of the piston 43 of a double-acting corrector cylinder 23 and at the other end 41 on a lug 21 rigid with the wheel support 22.

g Cylinder 23 is pivotally connected to a support 52 carried by wheel support 22.

rhe correction cylinders 23 of the two wheel suspensions are interconnected through pipe pipes 24, 25 leading from each side of the pistons 43, these pipe lines being supplied with pressure fluid from a distributor 26 controlled by the angular position -of the Vcentre arm 27 rigid with the anti-roll torsion bar 28 connecting the rearaxle swinging arms 22 to each other.

An anti-hunting spring 14 is located between the piston 18 and the bottom of the cylinder 19 of each wheel suspension. The spring load represents for example 10% of the reaction produced on the piston.

IIL-Distributor (Fig. 2)

ln the unloaded condition of the vehicle the lever 27 of the torsion bar is so positioned that the slide-valve of distributor 26 closes the two ports 24, 25 leading to the corrector cylinders 23. The hydraulic pressure inlet is thus balanced in the central groove 47 (Fig. 2).

When the suspension member 28, for example an antiroll torsion bar, rotates in the direction of the arrow F, the slide valve 26 is moved to the left and iluid under pressure is fed to the pipe line 24 and flows into the cylinder 23, thereby causing the piston 43 to move downwards and act through a rod 49 on the link 20, and increasing the distance measured from the fulcrum of the wheel support 22 on the frame to the pivoting connection 17 of the rod 44 of the suspension cylinder 19. The reverse occurs when the intermediate point 27 of the suspension member 28 rotates in the direction of the arrow F1, the slide valve 26 supplying the other pipe line 25.

IV.-Hydr0pneumatc suspension chamber The chamber 13 comprises two bell-shaped compartments 33, 34 subjected to the uid pressure from the wheel suspension cylinders 7, and 19 through pipe lines ,annales v- The pressure variations produced lin 'the'.front-wheelf suspension cylinders are.transmitterlrto the regir-aideyl-l inders through'the'nitrogen in '.the fcentral'jcomparnnent 36 of thehydro-pnenmaticsuspension chamber "13.

Bothfend compartments 33"and434 arelalso supplied with uid under 'pressure fromfthe "heightjcorrector' 16 through the "oil pipe line '51' 'to assure "ajconstant l'height of the vehicleand compensate any fiuidlleak'arge ,ifnrecesretain "automaticallyits 'balance since anyg'inclination of Ithe 'vehicle forwardly rnr rearwardly under the -inence of -any loadwill produce'anangnlardisplacementvof the ond-hydraulic suspension cylinders adapted to be secnred corresponding anti-roll torsion'barf-aboutits aXis=and the of wheels, a 'pairf-'of -irstfhydraulic suspension fcylinders adapted to lbelse'curcd'to I thefvehiclef chassis, far-first 'piston movable in; one of 'rsaid -rcylinders 2 and `connectedto f Yone of=said rods, asecond piston movablefin the-otherf'of said cylinders and connectedtothefother'ofisaidrrods, conduit means 1interconnecting wsaid suspension cylinders, 4fa Y hydraulic suspension chamber vfconnected to zsaid conduit means, =a`tirstfsuspension rmem'ber interconnect-ing the wheel.4 supports' of= said :oney pair` of wheels,'za;rst. distributor controlling dow of fluid in said suspensiomchamber, said distributor; havingan operating. elementsconnectedto the mid-pointV ofrsaid .suspension member, 3a rstflinkfpivoted at one end 4to a .wheelfsupport'iof the. other pair-.tof` wheelsfa second;link;pivoted..at,0ne end'tmthefotheiY wheel Supportof the othenpair ofwheels, ya pair-ofusec- 'to thevehielechassis, conduit means connecting said pair of second suspension cylinders to said suspension chamber, a iirstV piston movable in one of said second suspension cylinders and connected tothe mid-point of one of said links, a second piston-'movable in the other of said secondsuspension cylinders;v and connected to the mid pointofdhevther fof'v said links, ya l1pair of .:doublefacting correctork "cylinderstdtptevto libe, :securedto the L`.vehicle chassis, a piston in each corrector cylinder, a rod connectingv one o'f sidpistonsto one-of 'said"links, a -rod connecting the other of 'said pistons 'to `the other of said links, conduitgmeansiintercnxmecting isaid corrector cylinders, a second suspension member, intercmnectingthe wheelsupports-ofsidother -pziir 'of wheels, a second distributor controllingtsaidrcorrectoreylinders, said second distributor having an operating element connected to the mid- ,point of said.second'suspension member, and Vmeans interconnecting. sai'd,secondV distributor with said first distributor;

2. Inahydraulic*suspension system accordingjto .claim 1, antifhunt'rng springs'dislaosedl between thehpiston and bottom ofeachof said wheel suspension cylinders.

3. In aihydraulic suspensionsystem according to Claim 1, the` provisionV of 4athydrofpnenrnatie suspension chamber Y`comprising an enclosure Adivi-ded into three "aligned compartmentslbyapair ofresilient diaphragms, the 'cen- .tral compartment being iillefd'with -an'inert gas under pressurefeachfend compartmentbeng"connected on the oneE hand to the'frontfand rearwheel "suspension-'cylindersand-von the= other-"'handto` the Vheight corrector of lone of the ipairsy ofk wheels.v

4. Iniafhydral-icsuspension/accordingto-claim 1,the i controlling the supply of pressure uid to said cylindersl t whenthe vehicleisiunderfminimnm'load conditions and supplyingl pressnrertlnd 1 tof one or v the l"other: side off-the pistons of reacht-of usaid-l corrector :cylinders according v.to l y the :displacements Hof the zsupension Amember.

:ReferenceszCited inithewlezof this 'gpatent UNI-TED STATES 

